The natural rate of increase of a population is found by subtracting the death rate per 1000 people from the birth rate per 1000 people. Different factors affecting birth and death rates, such as fertility, disease, war, and so on, impact the rate of natural increase of the population. You can see the rate of natural increase in the top graph. In the bottom graph, you can choose a different starting year to simulate how the world's population would be affected in the following three years if conditions were to stay constant.

Contributed by: Chloe David and Nikki Menis(June 2016)Special thanks to the University of Illinois NetMath Program and the mathematics department at William Fremd High School.
Open content licensed under CC BY-NC-SA

Snapshots

Details

The top graph comes from data for the years 2000–2014 gathered from [2]; the rate of natural increase was calculated from a birth rate and death rate in a particular year. The curve between the dotted lines for birth rate and death rate (the dark green line) shows the actual rate of natural increase per 1000 people of the population for each year.

The bottom graph lets you choose a year with preset carrying capacities, birth rates, death rates, and starting populations; it is also based on real-world data from [2]. This yields a simulated growth plot of the next three years of the world's population. As carrying capacities depend heavily on current world conditions, all preset carrying capacities are equal to 60 billion, which is in an estimated range of possible carrying capacities of the Earth. You can also choose your own carrying capacity, birth rate, death rate, and starting population.

Snapshot 1: the year of the top graph is approximately 2008, and the bottom graph has custom conditions showing a slowly growing population: a carrying capacity of 60 billion, a starting population of 6 billion, a birth rate of 16.8, and a death rate of 15

Snapshot 2: the year of the top graph is approximately 2004, and the bottom graph has custom conditions showing a decreasing population: a carrying capacity of 60 billion, a starting population of 8 billion, a birth rate of 12.2, and a death rate of 13.1

Snapshot 3: all presets in this snapshot are of the year 2012

References

[1] World Population Prospects: The 2008 Revision, New York: United Nations Department of Economic and Social Affairs, Population Division.